Post on 26-Jan-2021
ADS-B: The Case for London Terminal Manoeuvring Area (LTMA)
Busyairah Syd Ali
©Thales
10th USA / Europe Air Traffic Management Research and Development Seminar (ATM 2013)
10 June 2013
Agenda
• Introduction
• System Overview
• Data Characteristics
• Data Evaluation Framework
• Results of Evaluation
• Findings
• Recommendations
• Conclusions
©Thales
©Thales
• Motivation - Article 4 of SPI-IR, clauses 3 and 4 - ANSP to ensure surveillance system complies to requirements - Operator to investigate and rectify avionics anomalies
• Hence the need for a framework to evaluate ADS-B performance - Challenges in the data analysis - Errors in the datasets - Recommendations
Introduction
System overview
Source Positioning performance
Data : British Airways
Onboard avionics performance
Data: NATS & BA
Ground station performance
Data: NATS
Data Link Mode-S 1090Mhz performance
Data: NATS
Data characteristics
Ground ADS-B ground stations (ASTERIX CAT021) Airborne Aircraft navigation system (GPS)
Data characteristics
Problems identified in the datasets
• Duplicate ADS-B messages, as recorded at ground level
• GPS clock errors as recorded on board the aircraft
• GPS position fluctuations recorded on board the aircraft
• Lack of consistent GPS position format output by the aircraft
• Uncorrelated time intervals between GPS data (at aircraft level) and ADS-B data (at ground level)
Each aircraft is assessed if it is suitable for the quantitative
performance analysis. Findings are recorded.
Data evaluation framework
Data evaluation framework: Data correlation
Difficulties in data correlation:
• Mismatch of update rates between data
• Inconsistent update rate of ADS-B data
• Lack of ADS-B data
• Different decimal precisions
• Time stamp differences
• Different horizontal position values GPS & ADS-B datasets
Data evaluation framework: Data correlation
Data evaluation framework: ‘Reference’
‘REFERENCE’ horizontal position derivation
The Reference (φREF, λREF) is derived as: φREF = φGPS + Δφ λREF = λGPS + Δλ where, φGPS is GPS latitude, λGPS is GPS longitude, Δφ , Δλ is the function of distance and azimuth based on latency and speed.
Assumption
ADS-B Specific
COMM
GS GPS
AVIONIC
SBAS, GBAS, RAIM
Results of Evaluation: ADS-B Latency
Definition – delay between aircraft position determination by on-board navigation system and position reception by ground station Potential sources for latency : •ADS-B ground station antenna delay •GPS antenna on the ground station (for clock) •Delay in the Flight Management System (FMS) (due to flight duration) •Interfacing between FMS to transponder (ADS-B emitter) •Interfacing between GPS receiver to transponder (ADS-B emitter) •Time error at the ground station •Data link delay (signal in space)
Results of Evaluation: ADS-B Latency
Latency Model = Δa + Δb + Δc + Δd + Δe
Δb varies based on DO-260/DO-260A or DO-260B configuration
Aircraft
GNSS
SIS
GPS Receiver
ADS - B
Emitter SIS (1090 MHz) ADS - B
Station /other Aircraft
Interface
Δ b Δ c Δ d Δ a
Δ e
Aircraft
GNSS
SIS
GPS Receiver
ADS - B
Emitter SIS (1090 MHz) ADS - B
Station /other Aircraft
Interface
Δ b Δ c Δ d Δ a
Δ e
Results of Evaluation: ADS-B Latency
Aircraft ID GPS Receiver ADS-B Emitter Mean Latency (second)
Standard Deviation (second)
40608F Thales TLS755 MMR Honeywell TRA-67A 1.7227 0.4851
405A48 Thales TLS755 MMR Honeywell TRA-67A 0.6289 0.2430
400A26 Thales TLS755 MMR Honeywell TRA-67A 1.9050 0.6485
400877 Thales TLS755 MMR Honeywell TRA-67A 0.6927 0.1615
400878 Thales TLS755 MMR Honeywell TRA-67A 0.5597 0.2627
40087B Thales TLS755 MMR Honeywell TRA-67A 1.7414 0.7008
4008B4 Thales TLS755 MMR Honeywell TRA-67A 0.5895 0.2760
4008F2 Thales TLS755 MMR Honeywell TRA-67A 0.6235 0.2584
400935 Thales TLS755 MMR Honeywell TRA-67A 0.7094 0.2158
Results of Evaluation: ADS-B Latency
Results of Evaluation: ADS-B Horizontal Position Accuracy
Analysis Method
Horizontal Position Error (HPE) assessment by:
comparing the received position with the REFERENCE position
Results of Evaluation: ADS-B Horizontal Position Error (HPE)
Aircraft ID GPS Receiver ADS-B Emitter RMS Position Error (meter)
40608F Thales TLS755 MMR Honeywell TRA-67A 476.2826
405A48 Thales TLS755 MMR Honeywell TRA-67A 66.2622
400A26 Thales TLS755 MMR Honeywell TRA-67A 552.8482
400877 Thales TLS755 MMR Honeywell TRA-67A 109.4822
400878 Thales TLS755 MMR Honeywell TRA-67A 113.1374
40087B Thales TLS755 MMR Honeywell TRA-67A 14287
4008B4 Thales TLS755 MMR Honeywell TRA-67A 30.8691
4008F2 Thales TLS755 MMR Honeywell TRA-67A 48.8772
400935 Thales TLS755 MMR Honeywell TRA-67A 145.4744
Results of Evaluation: ADS-B Horizontal Position Error (HPE)
Figure: Position error over time for aircraft 40087B
Figure: Position error distribution for aircraft 40087B
Results of Evaluation: ADS-B Horizontal Position Error (HPE)
Figure: Position error over time for aircraft 4008B4
Figure: Position error distribution for aircraft 4008B4
Results of Evaluation: ADS-B Horizontal Position Integrity
Analysis Method
• Position integrity quality indicator analysis
• Verification of integrity quality indicator
Results of Evaluation: ADS-B Horizontal Position Integrity
Quality Indicator (FOM) Analysis
N Min Max Mean Std. Dev
95676 0 8 5.43 2.62
Results of Evaluation: ADS-B Horizontal Position Integrity
Integrity Quality Indicator (NUC) Verification
Correct Detection (HPE < NUC < AL)
Missed Detection (NUC < AL < HPE)
False Alert (NUC < HPE < AL)
Displayed NUC = Actual Surveillance Performance???
Results of Evaluation: ADS-B Horizontal Position Integrity
Integrity Quality Indicator (FOM) Verification
Aircraft ID HPE (meters)
FOM Alert Limit (AL)
(meters)
Δ=AL-HPE Integrity Performance Category
40608F 476.2826 7
Results of Evaluation: ADS-B Availability
RTCA standard for Non Radar Airspace (NRA) : DO303
RTCA standard for Radar Airspace (RAD) : DO318
5 NM en-route separation: NUC = 4 3 NM separation: NUC = 5
5 NM en-route separation: NUC = 4 3 NM separation: NUC = 5
ADS-B reports received 81.8%
NUC/FOM > threshold
ADS-B reports availability 81.78%
Results of Evaluation: ADS-B Update Rate
Aircraft ID GPS Receiver ADS-B Emitter Mean Update Rate (second)
40608F Thales TLS755 MMR Honeywell TRA-67A 9.6
405A48 Thales TLS755 MMR Honeywell TRA-67A 1.1
400A26 Thales TLS755 MMR Honeywell TRA-67A 1.4
400877 Thales TLS755 MMR Honeywell TRA-67A 2.5
400878 Thales TLS755 MMR Honeywell TRA-67A 1.4
40087B Thales TLS755 MMR Honeywell TRA-67A 1.0
4008B4 Thales TLS755 MMR Honeywell TRA-67A 2.3
4008F2 Thales TLS755 MMR Honeywell TRA-67A 1.3
400935 Thales TLS755 MMR Honeywell TRA-67A 1.1
Findings
1. Unlike radar, ADS-B performance is aircraft dependent
2. ADS-B performance for each aircraft may differ due to: - Type of avionics - State of the communication link
3. Common failure modes - GNSS - ADS-B Ground Station
Recommendations
1. Signal jamming due to shared frequency use: - ADS-B - SSR Mode-S - TCAS
2. Quality indicator verification mechanism in the ground station
3. Ground station identification (ID) in ADS-B message
4. Onboard GPS time stamp in ADS-B message
Conclusion
• A comprehensive framework for the evaluation of ADS-B performance
• Identified various errors in the datasets which limited the performance evaluation
• Recommendations to improve ADS-B system performance and implementation
The methods proposed in this paper requires total collaboration between ANSP and airline
operators
Notification
Acknowledgements
• The Lloyd Register Foundation
• Malaysian-Imperial Doctoral Programme
• NATS UK
• British Airways
b.syd-ali@imperial.ac.uk The LRF Transport Risk Management Centre Centre for Transport Studies Imperial College London
Thank you…
ADS-B: The Case for London Terminal Manoeuvring Area (LTMA)AgendaIntroductionSystem overviewData characteristicsData characteristicsData evaluation frameworkData evaluation framework: Data correlation Data evaluation framework: Data correlation Data evaluation framework: ‘Reference’Results of Evaluation: ADS-B LatencyResults of Evaluation: ADS-B LatencyResults of Evaluation: ADS-B LatencyResults of Evaluation: ADS-B LatencyResults of Evaluation: �ADS-B Horizontal Position AccuracyResults of Evaluation: �ADS-B Horizontal Position Error (HPE)Results of Evaluation: �ADS-B Horizontal Position Error (HPE)Results of Evaluation: �ADS-B Horizontal Position Error (HPE)Results of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: �ADS-B Horizontal Position IntegrityResults of Evaluation: ADS-B AvailabilityResults of Evaluation: ADS-B Update RateFindingsRecommendations ConclusionNotificationAcknowledgementsThank you…